JP5741018B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus.

  As an electrophotographic image forming apparatus, a printer including a photosensitive drum on which an electrostatic latent image is formed and a developing roller that supplies toner to the photosensitive drum is known.

  In such a printer, as the printing is repeated, the toner component is thinly adhered to the surface of the photosensitive drum (so-called toner filming) or the surface of the photosensitive drum is worn, so that the surface state of the photosensitive drum is changed. May deteriorate.

  Therefore, for example, a detection sensor facing the non-image area of the photosensitive drum is provided, and a light beam is emitted from the light emitting portion of the detection sensor, and the light beam reflected by the surface of the photosensitive drum is received by the light receiving portion of the detection sensor An image forming apparatus that determines the life of a photosensitive drum from light quantity information received by a light receiving unit has been proposed (see, for example, Patent Document 1 below).

JP 2006-267702 A

  However, in the image forming apparatus described in Patent Document 1, the detection sensor includes a light emitting unit that emits a light beam and a light receiving unit that receives the light beam reflected by the surface of the photosensitive drum.

  That is, it is necessary to provide a light emitting unit and a light receiving unit in the detection sensor, and the configuration around the photosensitive drum is complicated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of determining the surface state of a photosensitive drum with a simple configuration.

  In order to solve the above-described problems, the present invention is an image forming apparatus, and scans the surface of the photosensitive drum along the axial direction of the photosensitive drum on which the electrostatic latent image is formed. As described above, the detection member includes an exposure member that emits light to the surface of the photosensitive drum, a first detection member that detects the intensity of reflected light of the light reflected by the surface of the photosensitive drum, and the detection And a determination unit that determines a surface state of the photosensitive drum based on detection of the means.

  According to this invention, the electrostatic latent image is formed on the surface of the photosensitive drum by the light from the exposure member, while the intensity of the reflected light of the light reflected from the surface of the photosensitive drum is detected by the first detection member, Based on the detection, the determination unit can determine the surface state of the photosensitive drum.

  That is, the surface state of the photosensitive drum can be determined using light for forming an electrostatic latent image on the surface of the photosensitive drum.

  As a result, the surface state of the photosensitive drum can be determined with a simple configuration without separately providing a member for emitting detection light to the photosensitive drum.

1 is a cross-sectional view of a printer as an embodiment of an image forming apparatus of the present invention. It is a bottom view of the exposure device shown in FIG. It is explanatory drawing explaining the detection of the reflected light by the sensor unit shown in FIG. 2, Comprising: It is a side view which shows the mode of the detection of the reflected light in the front-back direction. It is explanatory drawing explaining the detection of the reflected light by the sensor unit shown in FIG. 2, Comprising: It is a side view which shows the mode of the detection of the reflected light in the left-right direction. It is explanatory drawing explaining detection of the reflected light by the sensor unit shown in FIG. 2, Comprising: It is a graph which shows distribution of the intensity | strength of the reflected light detected by the sensor unit.

1. Overall Configuration of Printer As shown in FIG. 1, the printer 1 includes, in a main body casing 2, a paper feed unit 3 for feeding paper P and an image formation for forming an image on the fed paper P. Part 4.
(1) Main Body Casing The main body casing 2 is formed in a box shape having a substantially rectangular shape in side view that accommodates the paper feeding unit 3 and the image forming unit 4, and a process cartridge 10 to be described later is attached to and detached from one side wall thereof. A front cover 5 is provided so as to be swingable with respect to the main body casing 2 with a lower end portion as a fulcrum.

In the following description, the side on which the front cover 5 is provided (the right side in FIG. 1) is the front side, and the opposite side (the left side in FIG. 1) is the rear side. In addition, when the printer 1 is viewed from the front side, the left and right reference is used. That is, the front side in FIG. 1 is the left side, and the back side is the right side.
(2) Paper Feed Unit The paper feed unit 3 includes a paper feed tray 6 that accommodates the paper P. The paper feed tray 6 is detachably attached to the bottom of the main casing 2.

The paper P stored in the paper feed tray 6 is fed one by one toward the pair of registration rollers 8 by the rotation of the paper feed roller 7, and at a predetermined timing, the image forming unit 4 (photosensitive drum). 14 (to be described later) and a transfer roller 16 (to be described later).
(3) Image Forming Unit The image forming unit 4 includes a scanner 9 as an example of an exposure member, a process cartridge 10, and a fixing device 11.
(3-1) Scanner The scanner 9 is disposed on the upper part of the main body casing 2. Based on the image data, the scanner 9 emits a laser beam L as an example of light toward the photosensitive drum 14 (described later) (see the dotted line in FIG. 1), and exposes the photosensitive drum 14 (described later).
(3-2) Process Cartridge (3-2-1) Configuration of Process Cartridge The process cartridge 10 is detachably accommodated in the main body casing 2 below the scanner 9 and above the paper feed unit 3. 12 and a developing cartridge 13 that is detachably attached to the drum cartridge 12.

  The drum cartridge 12 includes a photosensitive drum 14, a scorotron charger 15, and a transfer roller 16.

  The photosensitive drum 14 is disposed at the rear end portion of the drum cartridge 12 and has a substantially cylindrical shape extending in the left-right direction. The photosensitive drum 14 has a photosensitive layer 26 made of a positively chargeable resin such as polycarbonate on the surface of a base tube 25 made of a metal such as aluminum.

  The scorotron charger 15 is disposed on the rear upper side of the photosensitive drum 14 so as to face the photosensitive drum 14 with a gap.

  The transfer roller 16 is disposed to face the lower side of the photosensitive drum 14 and is pressed against the photosensitive drum 14 from the lower side.

  The developing cartridge 13 includes a developing roller 17.

  The developing roller 17 is rotatably supported at the rear end portion of the developing cartridge 13 so as to be exposed from the rear side, and is pressed against the photosensitive drum 14 from the front side.

The developing cartridge 13 includes a supply roller 18 that supplies toner to the developing roller 17, and a blade 19 that regulates the thickness of the toner supplied to the developing roller 17. Yes.
(3-2-3) Development Operation in Process Cartridge The toner in the development cartridge 13 is supplied to the supply roller 18 and further supplied to the development roller 17 so that the positive polarity is provided between the supply roller 18 and the development roller 17. Frictional charge.

  The toner supplied to the developing roller 17 is regulated in thickness by the blade 19 as the developing roller 17 rotates, and is carried on the surface of the developing roller 17 as a thin layer having a constant thickness.

  On the other hand, the surface of the photosensitive drum 14 is uniformly positively charged by the scorotron charger 15 as the photosensitive drum 14 rotates, and then exposed by high-speed scanning of the laser beam L from the scanner 9. As a result, an electrostatic latent image corresponding to the image to be formed on the paper P is formed on the surface of the photosensitive drum 14.

  When the photosensitive drum 14 further rotates, the toner that is carried on the surface of the developing roller 17 and is positively charged is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 14. As a result, the electrostatic latent image on the photosensitive drum 14 is visualized, and a toner image by reversal development is carried on the surface of the photosensitive drum 14.

Then, when the sheet P conveyed between the photosensitive drum 14 and the transfer roller 16 passes between the photosensitive drum 14 and the transfer roller 16, the toner image carried on the photosensitive drum 14 is changed to the sheet P. Is transcribed.
(3-3) Fixing Device The fixing device 11 is disposed behind the process cartridge 10 and includes a heating roller 20 and a pressure roller 21 facing the heating roller 20. In the process cartridge 10, the toner image transferred onto the paper P is heat-fixed on the paper P by being heated and pressed while the paper P passes between the heating roller 20 and the pressure roller 21. .
(4) Paper Discharge Unit The paper P on which the toner image has been fixed passes through the paper discharge path 22 and is conveyed toward the paper discharge roller 23, and the paper discharge tray provided above the scanner 9 by the paper discharge roller 23. 24 is discharged.
2. Scanner (1) Configuration of Scanner As shown in FIGS. 1 and 2, the scanner 9 is formed in a substantially box shape. An opening 31 through which the laser beam L passes is formed at the bottom of the scanner 9.

  The opening 31 is formed at the rear end of the scanner 9 in a substantially rectangular shape in bottom view extending along the left-right direction so as to correspond to the paper width of the maximum size paper P that can be imaged by the printer 1.

The scanner 9 is provided with a transparent glass plate 32 that allows the laser beam L to pass therethrough so as to close the opening 31.
(2) Exposure of photosensitive drum by scanner As shown in FIG. 3, the scanner 9 applies laser to the photosensitive drum 14 so as to be inclined at a predetermined angle with respect to the normal line of the photosensitive drum 14 (see the virtual line in FIG. 3). The beam L is incident, and the laser beam L is moved at high speed in one axial direction of the photosensitive drum 14. Accordingly, the scanner 9 scans the surface of the photosensitive drum 14 along the axial direction of the photosensitive drum 14.

  Here, a part of the laser beam L incident on the photosensitive drum 14 is reflected on the surface of the photosensitive layer 26 of the photosensitive drum 14 so as to be symmetrical with respect to the incident direction with respect to the normal line of the photosensitive drum 14. Reflected in the direction.

  Specifically, the scanner 9 causes the laser beam L to be incident on the photosensitive drum 14 from the rear side so as to be inclined with respect to the normal line of the photosensitive drum 14, and moves the laser beam L at a high speed.

  Then, the reflected light R of the laser beam L is reflected to the front side of the opening 31 so as to be inclined forward with respect to the normal line of the photosensitive drum 14.

  Note that the reflected light R of the laser beam L is reflected so as to spread in a substantially conical shape when a part of the laser beam L is scattered in the photosensitive layer 26.

As a result, the reflected light R is reflected in a substantially strip shape extending in the left-right direction with a predetermined length in the front-rear direction as the scanner 9 scans the photosensitive drum 14. Further, a substantially strip-shaped reflected light incident area A on which the reflected light R is incident is formed on the bottom surface of the scanner 9 so as to extend in the left-right direction with a predetermined length in the front-rear direction.
3. Sensor Unit, CPU, and Storage Medium The printer 1 includes a sensor unit 41 as an example of three detection units, a storage medium 43 as an example of a storage unit, and a CPU 42 as an example of a determination unit.

  Each sensor unit 41 is provided in front of the opening 31 on the bottom surface of the scanner 9, and is arranged in parallel in the left-right direction at intervals.

  Each sensor unit 41 includes a first sensor 44 as an example of a first detection member disposed in the reflected light incident area A and a pair of first sensors disposed so as to sandwich the first sensor 44 in the front-rear direction. A second sensor 45 as an example of a second detection member, and a third sensor 46 as an example of a pair of third detection members arranged so as to sandwich the first sensor 44 in the left-right direction.

The first sensor 44, the second sensor 45, and the third sensor 46 are light receiving sensors that detect the intensity (I ₁ ) of the received reflected light R. The first sensor 44, the second sensor 45, and the third sensor 46 are each electrically connected to the CPU.

In the present embodiment, the sensor unit 41 is configured such that the intensity (I ₁₁ ) of the reflected light R detected by the first sensor 44 is the intensity of the reflected light R detected by the second sensor 45 and the third sensor 46 ( Positioning is maximized as compared to I ₁₂ and I ₁₃ ).

The storage medium 43 is provided in the main body casing 2 and is electrically connected to the CPU 42. As will be described later, the storage medium 43 stores the intensity (I ₀ ) of the reflected light R when the photosensitive drum 14 is new.

The CPU 42 is provided in the main body casing 2. As will be described later, the CPU 42 compares the intensity (I ₀ ) of the reflected light R stored in the storage medium 43 with the intensity (I ₁ ) of the reflected light R detected by each sensor unit 41. The surface state of the photosensitive drum 14 is determined.
4). Determination of the surface state of the photosensitive drum (1) Detection of reflected light in each sensor unit The determination of the surface state of the photosensitive drum 14 is performed, for example, after the printer 1 is turned on, and the printer 1 is prepared so that an image can be formed. Performed during the formation preparation operation.

  When the image forming preparation operation is started, as shown in FIG. 4 and as described above, predetermined points of the photosensitive drum 14 from the scanner 9 (in this embodiment, both the left and right ends of the photosensitive drum 14 and the central portion in the left and right direction). A laser beam L is emitted toward.

  Then, the reflected light R of the laser beam L is reflected to the front side of the opening 31 and received by the corresponding sensor unit 41 as described above.

  At this time, as described above, the reflected light R is reflected so as to spread in a substantially conical shape as a part of the laser beam L is scattered in the photosensitive layer 26.

Thereby, as shown in FIG. 5, the intensity (I ₁₁ , I ₁₂ , I ₁₃ ) of the reflected light R detected by each sensor (the first sensor 44, the second sensor 45, and the third sensor 46) is The first sensor 44 and the second sensor 45 are detected so as to be continuously distributed in the front-rear direction (direction perpendicular to the scanning direction of the scanner 9) (sub-scanning direction spectrum S1), and the first sensor 44 and the third sensor By the sensor 46, it is detected so as to be continuously distributed in the horizontal direction (scanning direction of the scanner 9) (scanning direction spectrum S2).

The intensity (I ₀₁ , I ₀₂ , I ₀₃ ) of the reflected light R detected by each sensor (first sensor 44, second sensor 45, and third sensor 46) when the photosensitive drum 14 is new is described above. As described above, it is stored in the storage medium 43 in advance.
(2) Determination of the surface state of the photosensitive drum by the CPU In order for the CPU 42 to determine the surface state of the photosensitive drum 14, the reflection detected by each sensor (the first sensor 44, the second sensor 45, and the third sensor 46). The intensity (I ₁₁ , I ₁₂ , I ₁₃ ) of the light R is compared with the intensity (I ₀₁ , I ₀₂ , I ₀₃ ) of the reflected light R stored in the storage medium 43.

For example, the intensity (I ₁₁ ) of the reflected light R detected by the first sensor 44 is greater than the intensity (I ₀₁ ) of the reflected light R stored in the storage medium 43, and the second sensor 45 and the third sensor 45 When the intensity (I ₁₂ , I ₁₃ ) of the reflected light R detected by the sensor 46 becomes smaller than the intensity (I ₀₂ , I ₀₃ ) of the reflected light R stored in the storage medium 43 (sub-scanning direction) When the peak intensities of the spectrum S1 and the scanning direction spectrum S2 increase and their spectral shapes become sharp), the thickness of the photosensitive layer 26 decreases and the reflected light R reflected on the surface of the base tube 25 is reflected. Judge that it has increased.

Further, for example, the intensity (I ₁₁ ) of the reflected light R detected by the first sensor 44 becomes smaller than the intensity (I ₀₁ ) of the reflected light R stored in the storage medium 43, and the second sensor 45 and When the intensity (I ₁₂ , I ₁₃ ) of the reflected light R detected by the third sensor 46 is greater than the intensity (I ₀₂ , I ₀₃ ) of the reflected light R stored in the storage medium 43 (secondary When the peak intensities of the scanning direction spectrum S1 and the scanning direction spectrum S2 decrease and the spectrum shapes become broad), filming occurs on the surface of the photosensitive layer 26, and a laser beam is generated on the surface of the photosensitive layer 26. It is determined that L is scattered.

Then, for example, when the intensity (I ₁₁ , I ₁₂ , I ₁₃ ) of the reflected light R detected by each sensor is within a predetermined numerical value range, the CPU 42 determines that the photosensitive drum 14 can be used. When the intensity (I ₁₁ , I ₁₂ , I ₁₃ ) of the reflected light R detected by the sensor exceeds a predetermined numerical value or becomes smaller than the predetermined numerical value, it is determined that the photosensitive drum 14 cannot be used. To do.

Thus, the CPU 42 determines the surface state of the photosensitive drum 14.
5. Operation and Effect (1) According to the printer 1, as shown in FIGS. 3 and 4, an electrostatic latent image is formed on the surface of the photosensitive drum 14 by the laser beam L from the scanner 9, while the surface of the photosensitive drum 14 is used. The first sensor 44 detects the intensity (I ₁ ) of the reflected light R of the laser beam L reflected at, and the CPU 42 can determine the surface state of the photosensitive drum 14 based on the detection.

  That is, the surface state of the photosensitive drum 14 can be determined using the laser beam L for forming an electrostatic latent image on the surface of the photosensitive drum 14.

As a result, the surface state of the photosensitive drum 14 can be determined with a simple configuration without separately providing a member for emitting detection light to the photosensitive drum 14.
(2) According to the printer 1, as shown in FIGS. 2 and 3, the sensor unit 41 includes a pair of second sensors 45 arranged in parallel in the front-rear direction with respect to the first sensor 44. .

Therefore, the first sensor 44 and the second sensor 45 can continuously detect the intensity (I ₁ ) of the reflected light R in the front-rear direction (the direction orthogonal to the scanning direction of the laser beam L).

As a result, the surface state of the photosensitive drum 14 can be determined based on the distribution of the intensity (I ₁ ) of the reflected light R in the front-rear direction.
(3) According to the printer 1, as shown in FIGS. 2 and 4, the sensor unit 41 includes a pair of third sensors 46 arranged in parallel in the left-right direction with respect to the first sensor 44. .

Therefore, the first sensor 44 and the third sensor 46 can continuously detect the intensity (I ₁ ) of the reflected light R in the left-right direction (scanning direction of the laser beam L).

As a result, the surface state of the photosensitive drum 14 can be determined based on the distribution of the intensity (I ₁ ) of the reflected light R in the left-right direction.
(4) According to this printer 1, as shown in FIGS. 2 and 4, a plurality (three) of sensor units 41 are provided so as to be arranged in parallel at intervals in the left-right direction. .

Therefore, the surface state of the photosensitive drum 14 can be determined at a plurality (three) of positions in the left-right direction (scanning direction of the laser beam L).
(5) According to this printer 1, the sensor unit 41 is provided on the bottom surface of the scanner 9 as shown in FIG. 2.

Therefore, the sensor unit 41 can be provided with a simple configuration using the bottom surface of the scanner 9 without separately providing a member for holding the sensor unit 41.
(6) According to the printer 1, the CPU 42 stores the intensity (I ₀ ) of the reflected light R stored in the storage medium 43 in advance when the photosensitive drum 14 is new and the reflection detected by the sensor unit 41. By comparing the intensity (I ₁ ) of the light R, the surface state of the photosensitive drum 14 is determined.

  Therefore, the current surface state of the photosensitive drum 14 can be compared with the surface state of the new photosensitive drum 14, and the current surface state (surface deterioration state) of the photosensitive drum 14 can be reliably determined. .

1 Printer 9 Scanner 14 Photosensitive drum 41 Sensor unit 42 CPU
43 Storage Medium 44 First Sensor 45 Second Sensor 46 Third Sensor L Laser Beam R Reflected Light

Claims (3)

A photosensitive drum on which an electrostatic latent image is formed;
An exposure member that emits light to the surface of the photosensitive drum so as to scan the surface of the photosensitive drum along the axial direction of the photosensitive drum;
Detection means having a first detection member for detecting the intensity of the reflected light of the light reflected by the surface of the photosensitive drum;
A determination unit that determines a surface state of the photosensitive drum based on detection by the detection unit ;
The exposure member includes a housing, and has an opening through which the light passes at a bottom portion of the housing,
The detection means includes
A second detection member disposed so as to sandwich the first detection member in a direction orthogonal to the axial direction, and detecting the intensity of the reflected light;
A third detection member disposed so as to sandwich the first detection member in the axial direction, and detecting the intensity of the reflected light;
The image forming apparatus is provided at a bottom portion of the housing at a position different from the opening . 2. The image forming apparatus according to claim 1 , wherein a plurality of the detection units are provided so as to be arranged in parallel at an interval in the axial direction. And a storage unit for storing the intensity of the reflected light when the photosensitive drum is new.
The determination unit determines the surface state of the photosensitive drum by comparing the intensity of the reflected light stored in the storage unit with the intensity of the reflected light detected by the detection unit. wherein, the image forming apparatus according to claim 1 or 2.

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